1. Technical Field
The present invention relates generally to an improved data processing system and, in particular, to a method and system for computer power control and power sequencing.
2. Description of Related Art
In the early 1980s, as the first PC""s were sold, people in the Information Systems (IS) industry thought that PC""s might replace mainframe computers and cut operating costs drastically. Over the years, as personal computers gained more functionality and better user interfaces, end-users improved their productivity and ability to generate data. While enterprise data and legacy applications were still placed on the more reliable mainframe platforms, there was more and more need for distributed access to application and data resources.
The IS industry succeeded in connecting the two worlds of PC""s and mainframes by implementing a client/server model with distributed databases. With the evolution of multi-platform applications over a variety of networking infrastructures, it appeared that PC""s might replace mainframe computers. However, as people in the IS industry realized the immense overall costs of this approach, the client/server model evolved in many directions.
The choice of a wider variety of computer platforms improves the enterprise""s ability to make appropriate investments in the evolving computing marketplace. Network Computers (NC""s) offer versatility because they have a built-in capability to run emulation software and to provide access to Java(trademark) and Windows(trademark)-based applications, such as browsers. NC""s are typically implemented with only a general purpose processor, a system memory, and a communications port. Although other types of peripheral devices may be included, local drives, such as hard disk and floppy drives, are characteristically absent from such data processing systems. While the primary reason for not providing a local drive within such data processing systems is cost-saving, other reasons may include low-power requirement, reliability, and compactness. Therefore, NC""s typically rely upon network access to provide dynamic, non-volatile data storage capability.
However, if the network computing environment is not managed properly, the administrative time and costs may be greater than those incurred in a traditional PC network. In addition, NC""s are vulnerable to power failures during which all of a user""s data will be lost because the data is usually temporarily stored in volatile memory in an NC.
Therefore, it would be useful to have a method and system for preserving user data in an NC when a power failure occurs.
A method and system for protecting user data during power failures on a network-computer-class data processing system is provided. The network-computer-class data processing system is integrated with a power supply having an early power fail warning signal to ensure that unsaved changes to user data files are saved before a complete power failure strikes the data processing system. As a user employs one or more applications to create or modify data files, a table of file changes is created for each user data file that is opened by the user. This table is kept in non-volatile media, preferably on the user""s network computer but possibly on a server located on a network connected to the network computer if the network computer lacks non-volatile memory. The entire contents of the table are saved to non-volatile storage in the time interval between the early power fail warning signal going active and the power completely failing. The table of user data changes can then be applied to recreate the user""s data after power is restored.